This invention relates to an assembly and method for absorbing the shock of an impact force on the components of a tripping mechanism of an circuit breaker during a fault current. More particularly, the preferred embodiment is a spring clip which is positively retained to a tripbar which absorbs the shock of a tripping mechanism moving at high velocity during a trip event.
Circuit breakers use various trip mechanisms to disconnect the circuit when a pre-determined event has occurred. Often the components of the trip mechanism are required to move at a high velocity as the result of a trip event and impact one another causing stress which can lead to structural or mechanical failure of one or more of the components.
Some circuit breakers use a trip mechanism which includes an electro-magnet which generates high magnetic forces when subjected to high fault currents in a circuit. The magnetic forces attract an armature or other similar component in order to close a gap between the armature and the electro-magnet. Displacement of the armature causes it to travel and impact another component such as a tripbar to continue the tripping sequence. The velocity of the armature travel can result in breaking the tripbar or armature. This is particularly a problem when the components such as the tripbar are made of a plastic material like a high glass thermal set phenoic.
An example of the problem experienced by the prior art is illustrated in FIG. 1. A tripping mechanism, generally designated as reference numeral 10, includes an electromagnet 12 which generates high magnetic forces 14 when the circuit (not shown) which the tripping mechanism is protecting experiences high fault currents. An armature 16 has one end 18 which is attracted by the magnetic forces 14, moving the armature towards the electromagnet 12 at a high velocity. The other end 20 of the armature 16 forms a hat 22 which includes a flange 24. A tripbar 26 is positioned within the line of motion of the armature 16 so that the flange 24 engages an impact area 28 on the tripbar as the armature 16 moves toward the electromagnet 12. The impact area 28 is offcenter from the rotational axis 30 of the tripbar. As the armature 16 travels toward the electromagnet 12 causing the flange 24 to engage the impact area 28, the tripbar 26 rotates in a counterclockwise motion indicated by arrow 32. The rotation of the tripbar 26 can then open the circuit by using the circuit breaker""s operating mechanism to open the contacts (not shown). The shock of the impact between the flange 24 striking the impact area 28 can cause the tripbar 26 to break.
There is a need for absorbing the shock of the impact between components of a trip assembly used in circuit breakers to prevent structural failure of the components.
The present invention provides a spring for a tripping mechanism in a circuit breaker for connection to a circuit. The tripping mechanism having a first component which is accelerated along a predetermined path of travel to a trip release velocity upon occurrence of a trip event in the circuit and a second component which is initially stationary prior to engaging the first component. The spring includes a body having integrally formed therein means for decreasing the trip release velocity of the first component prior to engaging the second component. The body is positioned along the pre-determined path of travel of the first component.
Preferably, the spring has a u-shape configuration which includes a bight defined between an upper leg and a lower leg. The upper leg defines a cantilever which extends from the bight to a far end. The far end has an upper surface defining a spring impact area for receiving engagement with the first component. The lower leg has means for mounting the spring to the second component.
The present invention also provides a tripbar for a tripping mechanism in a circuit breaker for connection to a circuit. The tripping mechanism has an armature which is accelerated along a predetermined path of travel to a trip release velocity upon occurrence of a trip event in the circuit while the tripbar is initially stationary prior to engaging the first component. The tripping mechanism further includes a spring having at least two ends. The tripbar includes an elongated body having a surface which has a slot for inserting one end of the spring therein. Means for stopping the deflection of the other end of the spring after the spring engages the armature is also included.
The present invention also provides a trip assembly for a circuit breaker for connection to a circuit. The trip assembly includes a first component which is set in motion along a predetermined path of travel to a trip release velocity by a trip event in the circuit. A second component is initially stationary prior to engagement with the first component. The assembly also includes means for decreasing the trip release velocity of the first component before it engages a second component.
The new and improved trip assembly of the present invention provides for the deceleration or shock absorption of the impact between two components.
It is an object of the present invention to prevent the breakage of components within a tripping mechanism that must engage when a trip event in the circuit releases the tripping mechanism.
Another object of the present invention is to provide a tripping mechanism which absorbs the impact shock between engaging components during a release of the mechanism while reliably resetting itself between trip events in the circuit.
Other and further advantages, embodiments, variations and the like will be apparent to those skilled in the art from the present specification taken with the accompanying drawings and appended claims.